This invention relates to a cordless telephone system having an automatic answering function.
Cordless telephone systems are generally composed of a master telephone set fixedly arranged to an office line, a portable and mobile slave telephone set, and a mobile charger connected to a commercial power supply to charge the battery of the slave telephone set.
Where there is conventionally a need of using in common the cordless telephone set and the automatic answering telephone set, user must connect these two telephone sets in parallel with the telephone line and use them.
In view of this, it is demanded to allow the cordless telephone set to have an automatic answering function. To realize this, it is devised to assemble an automatic answering circuit into the slave or master telephone set of the cordless telephone set. However, where the automatic answering circuit is assembled into the slave telephone set, it is impossible to keep the automatic answering standby state for a long time when dissipation of the battery is taken into account. Further, it is ordinary from a viewpoint of improvement in portability that the slave telephone set of the hand set unitary type. When a telephone of such a structure is employed, however, it is difficult to ensure the space of the speaker for reproduction or playback of message. On the other hand, where the automatic answering circuit is assembled into the master telephone set, since the contents of control signals intercommunicating between master and slave telephone sets vary in dependency upon whether the system is in a mode operating as an ordinary telephone set at the time of call incoming (ordinary mode) or in a mode operating at that time as an automatic answering telephone set (automatic answering mode), means for controlling this is further required, resulting in complicated structure and increased cost. In addition, since operations such as recording/reproduction of a message, etc. must be basically conducted by the master telephone set fixedly arranged, the merit of the cordless telephone that the slave set is mobile cannot be exhibited.